The present invention relates generally to generating displacement maps and more particularly to using parameterized sculpted meshes to generate displacement maps.
In creating animation or still images using computer generated imagery, there are a number of tools available to artists and processes that occur in generating images from structured geometric descriptions of a scene. In some images, it is desirable to have a modeled object that has a texture overlaid on the object. For example, a modeled object might be a building and the texture could be an image of a brick pattern. Overlaying an image texture onto an object can tend to give the object a flat appearance.
Bump maps can be used to provide an interesting surface. A bump map is a surface, typically represented as a two-dimensional array of displacement values and when the bump map is applied to the surface of the object, either (a) the surface of the object is displaced or (b) the surface normal is modified, by an amount indicated by the value of the bump map at the location of the bump map that corresponds to a particular location on the object. Thus, when a renderer is provided with the bump map and the geometric description of the object (and light sources, etc.) the output is an image where the surface of the object looks textured.
Bump maps are limited in that they can only displace the surface of the object in the direction of the surface normal at the displaced point on the surface of the object. However, vector displacement maps are known, wherein each point on the displacement map surface (or more technically, at each discrete point on the displacement map surface for which a value is stored), the displacement map has a vector value indicating the displacement, so it can be in directions other than the surface normal.
For various processing purposes, the modeled object and the displacement map are separate data structures. For example, there are some object manipulation steps that are easier when the object to be rendered is treated as an underlying object and an overlying vector displacement map rather than as an object that happens to have a surface that already agrees with the displacements.
In some tools, such as Mudbox, an artist or other user can create displacements for an object interactively. Then, once the textured object is specified, the tool will attempt to map points on the textured object back to points on the original object, using ray tracing. This is very computationally expensive and is not exact. Therefore, improved methods may have uses for artists, animators and other users.